No CrossRef data available.
We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
Published online by Cambridge University Press: 01 May 2009
I have, in the foregoing, endeavoured to set out the general conditions under which that one principal Glacial deposit of England which I term “Upper Glacial” was accumulated, according to the views to which I have been led by several years' active examination of the area occupied by it, and a still longer study of the phenomena observed. They differ materially in many respects from the views urged by Mr. Jas. Geikie in his “Great Ice Age,” and continued observation will help to determine which can best be reconciled with the facts; but before leaving the subject of this formation, I must observe that the diagram and description by Mr. Skertchly of the manner in which Lincolnshire was glaciated, as imported by Mr. Geikie into his book, conveys what I regard as an erroneous view.
page 14 note 1 Great Ice Age, p. 358. The diagram itself appears to be an application to the case of Lincolnshire of the one given by Mr. Tiddeman in illustration of the formation of Till in North Lancashire and the adjacent country, in the 28th volume of the Quart. Journ. of the Geol. Soc. p. 481.
page 15 note 1 There is some thin clay over the Permian north of Doncaster, but whether this is referable to the Glacial or to the Hessle clay I am unable to say. There is also much sand, which is partly capped by clay, between Retford and Doncaster, but these are to the west of the line referred to in the text. Beds of sand and gravel also cap the Liassic and Oolitic escarpments of the extreme N.W. of Lincolnshire. These were called by Mr. Rome and myself “Denudation sands,” but they may possibly represent the purple clay.
page 17 note 1 Quart. Journ. Geol. Soc. vol. xxiv. p. 146.Google Scholar
page 18 note 1 The distribution of this (Fen) gravel along the northern edge of the Fen and where it approaches near to the Hessle clay is shown in the map, and its position relatively to the chalky clay in section xv.
page 18 note 2 A stony clay, a few feet thick, which covers unconformably the Lower Glacial formation on the Norfolk coast, between Mundesley and Eccles (lat. 52° 48′ to 52° 51′), and which there rises to an elevation of about 40 or 50 feet above Ordnance datum, seems to belong to this formation. The molluscan fauna of the Hessle gravel and its equivalents in the East of England are given in the tabular list to the supplement to the “Crag Mollusca,” in the volume of the Palæontographical Society for 1873.
page 19 note 1 Quart. Journ. Geol. Soc. vol. xxx. p. 317.Google Scholar
page 21 note 1 It is not, indeed, unlikely that the polished and broken fragments of shells which occur in the gravels of some of the Welsh valleys, such as that of St. Asaph (some of which were sent me by Prof. Hughes), and even those in the Upper Boulder-clay and Middle Gravel of the North-western counties, of which several small collections from Cheshire and Lancashire have passed through my hands, got into these gravels and clays of the Hessle period in this way; and the same remark applies to the Caithness clay, the shells of which are promiscuously scattered through its mass, and are of a far less Arctic character than those of Elie and Errol. The glacier which during the minor glaciation filled the great valley of the Caledonian Canal probably at its commencement, ploughed out the marine gravels from that valley, and carried them into the Caithness clay then in course of formation.
page 22 note 1 A restoration of the supposed geographical features of the British Channel at this time according to my views is given in the fig. No. III. of the Sheet of Maps and Sections which accompanies my paper on the Weald in the 27th volume of the Quart. Journ. of the Geol. Soc.; see also Geol. Mag. Vol. III. p. 348.Google Scholar
page 23 note 1 Professor Phillips not only never recognized what we contended was the true position of the Hessle beds relatively to other Glacial or post-Glacial deposits, but he had not up to the time of our paper even recognized that the Hessle beds were distinct from the mass of the Glacial clay of Holderness, which latter he then regarded, not only as identical with the ordinary Glacial clay of East Anglia (Upper Glacial or great chalky clay), but as identical also with the (Lower Glacial) beds of Cromer Cliff.
page 23 note 2 Report of Brit. Assoc. for 1870, Geol. Mag. April, 1872, p. 176, and Sept. 1876, p. 396 (footnote). In a paper also “On the Climate of the Post-Glacial Period” in the same Mag. for April, 1872, p. 153, I drew attention to what appeared to me to be evidences of the recurrence of a glaciation of minor extent during that period.
page 24 note 1 See Quart. Journ. Geol. Soc. vol. xxiv. p. 174 (11. 1867)Google Scholar; vol. xxvii. p. 22 (Nov. 1870); Geol. Mag. 01. 1870, Vol. VII. p. 19; and April, 1872, Vol. IX. p. 176.Google Scholar
page 26 note 1 Latitude can have nothing to do with the presence of these shells, because, among the derivative fossils of either late Crag, or early Glacial age, found by Mr. Jamieson in gravels capped by Boulder-clay, near Aberdeen, which he sent me for examination, there was an undoubted fragment of Nucula Cobboldiæ, showing that this species had once lived there; and Tellina obliqua has been found associated with the other Upper Crag Tellens, in beds in Iceland, whose fossils correspond with the later Crag beds. If, as I suspect, most of the ice-formed beds of Scotland belong to the minor glaciation, the ice of which destroyed the preceding beds as far as it extended, the derivative molluscan remains found by Mr. Jamieson probably constitute part of the wreck of the deposits of the first or major period of glaciation in that country.
page 27 note 1 The Wexford gravels, if the fauna given from them he reliable, would also seem to be a remnant of the beds of the earlier glaciation in Ireland; for along with some other peculiar forms, a fragment of Nucula Cobboldiæ is mentioned by Forbes as having been found in them. It is, however, possible that this fragment might have been one of Lucina (Loripes) divaricata, a living British shell.
page 27 note 2 The place is indicated on the accompanying map, where also the dotted line shows the position of the Chalk floor down to which, from contiguous borings, the chalky clay has been found to descend.
page 28 note 1 Except the derivative fragment found by Mr. Jamieson in the gravel near Aberdeen, referred to in a previous note on p. 26.
page 28 note 2 Five living species of Nucula with divaricated markings like Cobboldiæ are known. They are confined to the Pacific Ocean, and have been described under the following names, viz. N. mirabilis (from Japan), N. divaricata (China Sea), N. insignis (Japan), N. castrensis (Sitka), and N. Lyalli (Vancouver). The first named is about one-third of the size of the full-grown Cobboldiæ, while none of the others exceed a ninth; and their hinge-teeth are from 4 to 9 fewer. The divaricated marks in all five extend to the margin of the shell, while Gobboldiæ has round this margin a broad belt which is free from them. It is possible, though hardly probable, that all the specimens yet obtained of these five species are those of young individuals which might have grown into a mature shell like Cobboldiæ; but until a specimen of the kind can be produced, it is as reasonable to identify any of these Pacific species with Cobboldiæ, as with the divaricated Nuculæ from the Gault.
page 29 note 1 MrReade, T. M., Quart. Journ. Geol. Soc., vol. xxx. p. 30, gives shells from apparently this clay (Brick clay) at 175 feet.Google Scholar
page 29 note 2 This list, in so far as it refers to the occurrence in the Crag of species named in it, contains several inaccuracies.